Hi

I am not sure about the structure of your Database and tables. I assume that you have properly designed table and forms for data entry. If so try the following.

I hope you have a table for your “order entry”, another table with customerid and limit. Hope you are inputting the orders into the order table through a form. If so, create two textboxes on the same form. On the first text box, bring the limit using Dlookup function from “Limit Table”. On the second text box bring the sum of the total orders using Dsum function from your “Order table”. When you click the button to add your new entry to Table Orders, check both these value and continue if conditions are met other wise use a warning message and stop addition of the new entry.
Regards

Mac